The use of implantable access ports in the art of drug therapy is well known, in which an access port is implanted beneath the subcutaneous layers of a patient's skin. The known access ports are constructed to provide for repeated access to the vascular system of a patient, or a selected treatment site within the patient's body. The use of these devices reduces the trauma otherwise associated with multiple punctures of the skin, or the inconvenience of an externalized catheter for patient treatment purposes. For example, implantable access ports are used to facilitate frequent blood sampling, or to provide for the delivery of medications, nutritions, blood products, and imaging solutions into the patient's blood stream, or to a desired treatment site within the patient. Access to the implanted device/port is typically accomplished by percutaneous needle insertion through the patient's skin into the access port through a penetrable septum or other similar structure by using a non-coring hypodermic needle.
Implantable access ports are supplied as sterile devices, are provided for single patient use only, and are available in a variety of port materials, including polysoufone, acetal plastic and titanium. Available catheter materials include polyurethane and silicone. Suture holes are typically formed in the access port as a part of the base portion thereof and are used to facilitate the anchorage of the access port to the patient's underlying fascia, for example muscle. Implantable access ports are available in single, dual, and low profile models, and are available with attachable, or attached catheters.
A major problem with implanted vascular access systems, and in particular access ports, is the occlusion of the system by coagulated blood or other material between uses. As known, occlusion occurrences can lead to patient complications such as systemic infection, pocket infection, extravasation of medications, and port failure, all of which may lead to an explant of the device. Further, most patients that receive implantable access ports are either immune compromised, or are in danger of becoming immune compromised. These complications can therefore have a serious effect on the patient. As known, there are clinical steps that can be taken to prevent this occurrence, such as flushing and infusion of the access port with a saline solution. The growth of such occlusive substances, however, occurs through time and appears to occur at a much higher rate in access ports with edges and gaps present in the flow path.
For example, one well known type of access port has a cylindrical reservoir formed within the base of the access port, an example of which is disclosed in U.S. Pat. No. 5,041,098 to Loiterman et al. Although access ports with cylindrical reservoirs have proven to be quite successful and gained wide acceptance and usage as described above, problems do exist with this type of construction. Namely, there are angular corners or junctions formed where the respective side walls of the reservoir join the bottom and top walls, respectively, forming the reservoir, and the outlet passageway is typically defined with the side wall of the reservoir such that it is spaced from (above) the bottom wall or surface of the reservoir. So defined, the outlet/outlet passageway forms a small ledge or catch pocket in the reservoir which may lead to the occlusion of blood or other substances passed into or drawn from out of the access port.
Additionally, access ports with cylindrical reservoirs typically enclose a large amount of space which results in a large volume of fluid that must flow into the access port during use, and which fluid remains in the port thereafter. This extra fluid also reduces the efficiency of flushing protocols by requiring larger flows of fluid over extended times to completely flush the reservoir after use. This is further compounded by the positioning of the outlet passageway at a central location within the reservoir side wall such that a gap exists between the bottom of the reservoir and the entrance to the outlet passageway.
What is needed, therefore, is an implantable access device with an improved reservoir configuration which will further reduce the occurrence of occlusion by improving upon the technology of reservoir designs. Moreover, there is a need for such an improved reservoir design coupled with a more efficient means of draining fluids and other materials from the reservoir of the access port during and after the usage of the port.